Gasoline compositions with improved octane number

ABSTRACT

The present invention aims a new gasoline composition comprising a gasoline fuel and from 0.05 to 1% of a specific low quantity of a glycerol ketal or acetal. The new gasoline composition shows a higher octane number compared to known gasoline compositions. The invention also aims at the use of said glycerol ketal or acetal as a metal free octane booster additive for octane adjustment of gasoline compositions.

FIELD OF THE INVENTION

The present invention relates to a new gasoline composition containing a specific low quantity of glycerol ketal or acetal as an additive able to boost the octane number of the gasoline composition. The invention also aims at the use of said glycerol ketal or acetal as a metal free octane booster additive for octane adjustment of gasoline compositions.

BACKGROUND OF THE INVENTION

Gasoline, also known as petrol outside of North America, is a transparent, petroleum-derived liquid that is used primarily as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives.

Spark ignition engines are designed to burn gasoline in a controlled process called deflagration. However, the unburned mixture may autoignite by detonating from pressure and heat alone, rather than ignite from the spark plug at exactly the right time. This causes a rapid pressure rise which can damage the engine. This is often referred to as engine knocking or end-gas knock. Knocking can be reduced by increasing the gasoline's resistance to autoignition, which is expressed by its octane number.

Indeed, the characteristic of a particular gasoline blend to resist igniting too early (which causes knocking and reduces efficiency in reciprocating engines) is measured by its octane number. Gasoline is produced in several grades of octane numbers.

Octane number is measured relative to a mixture of 2,2,4-trimethylpentane (an isomer of octane) and n-heptane. The second one has an octane number of 0, while iso-octane (2,2,4-trimethyl pentane) is 100. Linear combinations of these two components are used to measure the octane number of a particular fuel. A 90%/10% blend of isooctane/n-heptane has an octane value of 90. Any fuel knocking at the same compression ratio as this mixture is said to have an octane number of 90.

There are different conventions for expressing octane numbers, so the same physical fuel may have several different octane ratings based on the measure used. One of the best known is the research octane number (RON).

Research Octane Number (RON) is measured in mild conditions (inlet temp and RPM), indicative of normal road performance, while Motor Octane Number (MON) is measured in severe conditions (inlet temp and RPM), indicative of high speed performance. The spread between the two numbers (MON&RON) is known as the fuel sensitivity. Classically, both numbers are measured with a standardized single cylinder, variable compression ratio engine. For both RON and MON, the engine is operated at a constant speed (RPM'S) and the compression ratio is increased until the onset of knocking. For RON engine speed is set at 600 rpm and MON is at 900 rpm.

Gasoline is produced in oil refineries from crude oil.

The bulk of a typical gasoline consists of hydrocarbons with between 4 and 12 carbon atoms per molecule (commonly referred to as C4-C12). It is a mixture of paraffins (alkanes), cycloalkanes (naphthenes), and olefins (alkenes), where the usage of the terms paraffin and olefin is particular to the oil industry. The actual ratio depends on:

-   -   the oil refinery that makes the gasoline, as not all refineries         have the same set of processing units;     -   the crude oil feed used by the refinery;     -   the grade of gasoline, in particular, the octane rating.

The various refinery streams blended to make gasoline have different characteristics. Some important streams are:

-   -   straight-run gasoline, usually also called naphtha is distilled         directly from crude oil. Once the leading source of fuel, its         low octane rating required lead additives. It is low in         aromatics (depending on the grade of crude oil), containing some         cycloalkanes (naphthenes) and no olefins (alkenes). Between 0         and 20% of this stream is pooled into the finished gasoline.     -   reformate, produced in a catalytic reformer has a high octane         rating with high aromatic content, and relatively low olefins         (alkenes). Most of the benzene, toluene, and xylene (the         so-called BTX) are more valuable as chemical feedstocks and are         thus removed to some extent.     -   catalytic cracked gasoline or catalytic cracked naphtha,         produced from a catalytic cracker, with a moderate octane         rating, high olefins (alkene) content, and moderate aromatics         level.     -   hydrocrackate (heavy, mid, and light) produced from a         hydrocracker, with medium to low octane rating and moderate         aromatic levels.     -   alkylate is produced in an alkylation unit, using as feedstocks         isobutane and alkenes. Alkylate contains no aromatics and         alkenes and has high MON.     -   isomerate is obtained by isomerizing low octane straight run         gasoline to iso-paraffins (non-chain alkanes, like isooctane).         Isomerate has medium RON and MON, but nil aromatics and olefins.     -   butane is usually blended in the gasoline pool, although the         quantity of this stream is limited by the Reid Vapor Pressure         specification; which regulates the volatility of gasoline.

The terms above are the jargon used in the oil industry and terminology varies.

Gasoline can also contain other organic compounds, such as organic ethers (deliberately added), plus small levels of contaminants, in particular organosulfur compounds, but these are usually removed at the refinery.

Gasoline generally also comprises various additives like:

-   -   Alcohols: Methanol, Ethanol, Isopropyl alcohol, n-butanol,         Gasoline grade t-butanol;     -   Ethers: Methyl tert-butyl ether (MTBE), now outlawed in many         states of the U.S. for road use, mostly because of water         contamination, Tertiary amyl methyl ether (TAME), Tertiary hexyl         methyl ether (THEME), Ethyl tertiary butyl ether (ETBE),         Tertiary amyl ethyl ether (TAEE), Diisopropyl ether (DIPE);     -   Antioxidants, stabilizers: Butylated hydroxytoluene (BHT),         2,4-Dimethyl-6-tert-butylphenol, 2,6-Di-tert-butylphenol         (2,6-DTBP), p-Phenylenediamine, Ethylene diamine;     -   Antiknock agents: Tetraethyllead, Methylcyclopentadienyl         manganese tricarbonyl (MMT), Ferrocene, Iron pentacarbonyl,         Toluene, Isooctane, Triptane     -   Lead scavengers (for leaded gasoline): Tricresyl phosphate         (TCP), 1,2-Dibromoethane, 1,2-Dichloroethane;     -   Fuel dyes, most common: Solvent Red 24, Solvent Red 26, Solvent         Yellow 124, Solvent Blue 35.

Tetraethyllead and other lead compounds are no longer used in most areas to regulate and increase octane-rating because of health and environment concerns.

Methylcyclopentadienyl manganese tricarbonyl (MMT) is used in Canada and in Australia to boost octane, but its use in the US has been restricted by regulations.

U.S. Pat. No. 4,390,345 describes the use of 1,3-dioxolane and lower alkyl or alkenyl derivatives thereof as exhaust hydrocarbon emissions reducers for MMT antiknock containing gasoline compositions. As explained before, the use of MMT containing gasoline compositions is now restricted because of its toxicity for environment.

EP2298851 discloses the use of a blend of Alcohol and cyclic ketal at minimum 10% by weight of the gasoline composition in order to improve the octane number of the composition. It is also specified that the use of 10% by weight of a glycerol-acetone cyclic ketal in gasoline increases the octane number by 1.4 units.

There are several units in the refinery which are ending up recycling and upgrading naphta into components that end up in the gasoline pool/blending facility of the refinery, including high and low octane components which are blended to produce commercial grade of gasoline with the desired octane number.

In the process of blending, all the specification parameters need to be met, such as distillation curves and Octane Numbers. There are 2 types of Octane improvers:

-   -   Blending Components: They are used in high percentages, usually         around 10-20% in the blending process. For example MTBE (under         scrutiny for toxicity) and Ethanol;     -   Octane Booster Additives: They are used to increase the Octane         Number of Final Blends. Usually 2000 to 10000 ppm max to meet         the desired RON number

It is difficult to blend gasoline, meeting all the technical parameters and always meeting the final Octane target; because most of the calculations are done by computer simulations and most of the blending is done in huge quantity with operation volume losses in cargoes or pipelines. For example, you could finish your blend of a gasoline with an expected RON at 98 with all the specifications correct and when you make your final sample tests (top, middle and bottom of storage tank), your average RON is at 97.8. In this case you have to add Octane boosters which are mixed into the tank in a less than 12 hours operation. Currently the main technologies are metals, Manganese (MMT) or Iron (ferrocene) for example. These technologies are under a lot of scrutiny due to emission effects.

One of the objects of the invention is to propose an improved metal free high octane number gasoline composition with a reduced emission impact during combustion.

A further object of the invention is to propose a metal free non-toxic octane booster additive for octane adjustment of gasoline compositions which is effective at low dosage.

Another objective of the present invention is to propose a metal free non-toxic octane booster additive for octane adjustment of gasoline compositions that is at least partially originated from bio-resources.

SUMMARY OF THE INVENTION

The invention thus proposes a metal-free gasoline composition comprising at least one gasoline fuel and from 0.05 to 1% by weight of an octane booster additive comprising at least one compound of formula I below:

wherein

R₁ and R₂, independently from one another, are selected in the group consisting of: a linear or branched C1-C12 alkyl, a C4-C12 cycloalkyl or an aryl.

R₃ is H, a linear or branched alkyl, a cycloalkyl or a C(═O)R₄ group, with R₄ being a linear or branched C1-C4 alkyl or a C5-C6 cycloalkyl.

The present invention also proposes the use of from 0.05 to 1% by weight of a composition comprising at least one compound of formula I described above according to all the possible embodiments and combinations thereof as an octane number booster additive for a gasoline composition. In particular, the use is as octane booster additive to adjust the octane number of a blended gasoline fuel.

DETAILED DESCRIPTION OF THE INVENTION

The metal-free gasoline composition of the invention comprises at least one gasoline fuel and from 0.05 to 1% by weight of an octane booster additive comprising at least one compound of formula I below:

wherein

R₁ and R₂, independently from one another, are selected in the group consisting of: a linear or branched C1-C12 alkyl, a C4-C12 cycloalkyl or an aryl.

R₃ is H, a linear or branched alkyl, a cycloalkyl or a C(═O)R₄ group, with R₄ being a linear or branched C1-C4 alkyl or a C5-C6 cycloalkyl.

In a preferred embodiment, R₁ and R₂, independently from one another, are selected in the group consisting of: methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, tert-butyl, n-pentyl, cyclopentyl, cyclohexyl or phenyl.

Advantageously, in formula I above R₃ is H or a C(═O)R₄ group, with R₄ being methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl or tert-butyl.

One preferred embodiment is when R1 and R2 are methyl and R3 is H. In this case, the compound is commercially available, for example under the name Augeo® Clean Multi, Augeo® SL191 or Solketal. This compound can be synthesized by reaction between glycerol and acetone, under well-known classical conditions.

In another embodiment, R1 is methyl, R2 is isobutyl and R3 is H. In this case, the compound is commercially available, for example under the name Augeo® Clean Plus. This compound can be synthesized by reaction between glycerol and methyl-isobutyl ketone, under well-known classical conditions.

In a third embodiment, R1 is methyl, R2 is phenyl and R3 is H. In this case, the compound is commercially available, for example under the name Augeo® Film HB. This compound can be synthesized by reaction between glycerol and acetophenone, under well-known classical conditions.

Another possibility is to have R1 and R2 are methyl and R3 is a C(═O)R4 group, with R4 being methyl. In this case, the compound is commercially available, for example under the name Augeo® ACT. This compound can be synthesized by transesterification of Solketal with an alkyl acetate under well-known classical conditions.

Glycerol can be obtained as a co-product from biodiesel production during the transesterification of triglycerides. Glycerol is thus a product that can come from bio-resources.

Usual Octane enhancing compounds are not environment friendly: lead additives are toxic air pollutants and poison catalytic converter catalysts. In Gasoline, benzene is carcinogenic, aromatics produce more smoke and smog and olefins form engine fouling gums, more smoke & smog.

The compounds of formula I of the invention have very good performance in the application, low odor and no toxicity to humans or environment. In addition, their use induces no security issues because of their high flash point. There are sustainable alternatives to existing octane boosters in gasoline application as they meet the three pillars of sustainability (economical, environmental and social).

It is also a favorable embodiment when a blend of two or more compounds of formula I is used in the gasoline composition according to the invention. This blend preferably comprises Augeo® Clean Multi and Augeo® Clean Plus, in a weight ratio from about 30:70 to 70:30, and even more preferably 50:50. Another advantageous blend comprises Augeo® Clean Plus and Augeo® ACT, in a weight ratio from 30:70 to 70:30, and even more preferably 60:40.

One possible embodiment is when the octane booster additive consists in one or more compounds of formula I.

Also, the octane booster additive of the gasoline according to the invention can further comprise esters of C1-C6 carboxylic acids and/or ketones such as butyl acetate, propyl acetate, Methyl Isobutyl Ketone and Methyl Ethyl Ketone, advantageously ethyl acetate. According to this embodiment, the molar ratio of compound of formula I/esters of C1-C6 carboxylic acids and/or ketones, and in particular the molar ratio of compound of formula I/ethyl acetate can be from 30:70 to 100:0, preferably from 50:50 to 95:5.

In brief, according to the invention “from 0.05 to 1% by weight of an octane booster additive comprising at least one compound of formula I” means that the octane booster can be either 100% at least one compound of formula I or can comprises a minimum of 0.015% of at least one compound of formula I, the rest being esters of C1-C6 carboxylic acids and/or ketones such as butyl acetate, propyl acetate, Methyl Isobutyl Ketone and Methyl Ethyl Ketone, advantageously ethyl acetate.

In the gasoline composition according to the invention, it is particularly preferred to have the octane booster additive present in an amount of 0.1 to 1.0%, preferably from 0.2 to 1% and even more preferably 0.2 to 0.8% by weight of the total weight of the gasoline composition.

The gasoline fuel can comprise a complex mixture of light hydrocarbons containing 5-12 carbon atoms produced in oil refineries. Gasoline is composed of over 200 chemicals, such as: benzene (up to 5%), Toluene (up to 20%), naphthalene (up to 2%), trimethylbenzene (up to 5%) and others.

The present invention also proposes the use of from 0.05 to 1% by weight of a composition comprising at least one compound of formula I described above according to all the possible embodiments and combinations thereof as an octane number booster additive for a gasoline composition. In particular, the use is as octane booster additive to adjust the octane number of a blended gasoline fuel.

All the specific embodiments described above for the gasoline composition also apply to the use above mentioned.

The introduction of the compound of formula I above into gasoline leads to gasoline motor fuels making it possible to increase the octane number with respect to a fuel not containing the products in question. For example, the invention surprisingly, at a such low dosage of 1% of Augeo SL191, allows an increase in the octane number of 0.6, which is well above the expectations of the prior art.

The following examples illustrate the invention in a non-limiting way.

DESCRIPTION OF THE FIGURES

FIG. 1 to 3 correspond to octane number (RON and MON) measurement diagrams as a function of the quantity of Augeo® SL191 added for three different gasoline fuels. Those figures are related to Examples 1 to 3.

FIGS. 4 and 5 are octane number (RON and MON) measurement diagrams as a function of the quantity of Augeo® SL191 and ethyl acetate added to two different gasoline fuels, as described in Examples 4 and 5.

EXAMPLES Methods of Measure

For the examples below, the parameters have been measured according to the standards indicated in the below table I.

TABLE I methods of measure RON MON NF EN ISO 5164 NF EN ISO 5163

Tests and Results

Octane number results (RON and MON) have been measured for different types of gasoline, after addition of different additives, followed by a reasonable time of stirring (approximately 10 minutes). Results are as shown in examples 1 to 5 below.

Example 1: 95 RON Gasoline (Unleaded Oxy Free)—Augeo® SL191

This type of gasoline is indicated to high performance automobiles because its RON specification is minimum 95. It's availability will depend on each region needs and habits, but it is quite common in Europe and some countries of Latin America, for example.

Augeo SL191, which is commercially available, was added in the concentrations indicated below, and the octane numbers were measured according with the standard already mentioned. The table II below indicates the results obtained.

TABLE II 95 RON Gasoline Details Gasoline Legislation NF EN ISO 5164 NF EN ISO 5163 % (w/w) Augeo SL191 RON MON 0.00 95.8 85.3 1.00 96.4 85.6

The diagram of this example is presented on FIG. 1.

Example 2: Unleaded Gasoline 91—Augeo® SL191

Gasoline that, despite of the minimum RON of 91 as specification, also requires no lead content. It's availability will depend on each region needs and habits, but it is quite common in Australia and New Zeland, for example.

Augeo SL191, which is commercially available, was added in the concentrations indicated below, and the octane numbers were measured according with the standard already mentioned. The table III below indicates the results obtained.

TABLE III Unleaded Gasoline 91 Details Gasoline Legislation NF EN ISO 5164 NF EN ISO 5163 % (w/w) Augeo SL191 RON MON 0.00 90.4 83.3 0.20 90.7 83.8

The diagram of this example is presented on FIG. 2.

Example 3: SP95—Augeo® SL191

SP95 means “sans plomb”, which in french means unlead, and 95 is the minimum RON required. It's availability will depend on each region needs and habits, but it is quite common in Europe, for example.

Augeo SL191, which is commercially available, was added in the concentrations indicated below, and the octane numbers were measured according with the standard already mentioned. The table IV below indicates the results obtained.

TABLE IV SP95 Details Gasoline Legislation NF EN ISO 5164 NF EN ISO 5163 % (w/w) Augeo SL191 RON MON 0.00 96.1 85.3 0.20 96.3 85.3

The diagram of this example is presented on FIG. 3.

Example 4: Unleaded Gasoline 91—Augeo® SL191 and Ethyl Acetate

A blend of 50% by weight of Augeo SL191 and 50% of ethyl acetate, which are both commercially available, was prepared and then was added in the concentrations indicated below, and the octane numbers were measured according with the standard already mentioned. The table V below indicates the results obtained.

TABLE V Unleaded Gasoline 91 Details Gasoline Legislation NF EN ISO 5164 NF EN ISO 5163 % (w/w) 50% Augeo SL191 50% Ethyl Acetate RON MON 0.00 90.4 83.3 0.20 90.9 83.9

The diagram of this example is presented on FIG. 4.

Example 5: SP95—Augeo® SL191 and Ethyl Acetate

A blend of 50% by weight of Augeo SL191 and 50% by weight of ethyl acetate, which are both commercially available, was prepared and then was added in the concentrations indicated below, and the octane numbers were measured according with the standard already mentioned. The table VI below indicates the results obtained.

TABLE VI SP95 Details Gasoline Legislation NF EN ISO 5164 NF EN ISO 5163 % (w/w) 50% Augeo SL191 50% Ethyl Acetate RON MON 0.00 96.40 85.00 0.50 96.90 85.40 1.00 97.10 85.50

The diagram of this example is presented on FIG. 5.

Comparative Example: Unleaded Gasoline Alcohol Free—Augeo® SL191 1.45%

Augeo® SL191, which is commercially available, was added in the concentrations indicated below, and the octane numbers were measured according with the standard already mentioned. The table VII below indicates the results obtained.

TABLE VII Unleaded gasoline Details Gasoline Legislation NF EN ISO 5164 NF EN ISO 5163 % (w/w) Augeo SL191 RON MON 0.00 94.9 85.7 1.45 94.8 85.5

The above results show that at quite low dosage of the components of Formula I by themselves or as a blend with esters are able to improve the octane number of different types of gasoline, and both the RON and MON parameters. On the contrary, by addition of a higher quantity of Augeo SL191 (see comparative example) in the gasoline the octane booster effect disappears. 

1. A metal-free gasoline composition, comprising at least one gasoline fuel and from 0.05 to 1% by weight of an octane booster additive that comprises at least one compound according to formula I:

wherein: R₁ and R₂, independently from one another, are selected from the group consisting of linear or branched C1-C12 alkyl, C4-C12 cycloalkyl, and aryl, R₃ is H, linear or branched alkyl, cycloalkyl, or —C(═O)R₄, and R₄ is linear or branched C1-C4 alkyl or C5-C6 cycloalkyl.
 2. A gasoline composition as claimed in claim 1, wherein R₁ and R₂, independently from one another, are selected from the group consisting of: methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, tert-butyl, n-pentyl, cyclopentyl, cyclohexyl, and phenyl.
 3. A gasoline composition as claimed in claim 1, wherein R₃ is H or —C(═O)R₄ wherein R₄ is methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl or tert-butyl.
 4. A gasoline composition as claimed in claim 1, wherein R₁ and R₂ are each methyl and R₃ is H.
 5. A gasoline composition as claimed in claim 1, wherein R₁ is methyl, R₂ is isobutyl, and R₃ is H.
 6. A gasoline composition as claimed in claim 1, wherein R₁ is methyl, R₂ is phenyl, and R₃ is H.
 7. A gasoline composition as claimed in claim 1, wherein R₁ and R₂ are each methyl, R₃ is —C(═O)R₄ and R₄ is methyl.
 8. A gasoline composition as claimed in claim 1, wherein the octane booster additive comprises a blend of two or more compounds of formula I.
 9. A gasoline composition as claimed in claim 1, wherein the octane booster additive further comprises esters of C1-C6 carboxylic acids and/or ketones.
 10. A gasoline composition as claimed in claim 1, wherein the octane booster additive optionally further comprises esters of C1-C6 carboxylic acids and/or ketones, in a molar ratio of compound of formula I/esters of C1-C6 carboxylic acids and/or ketones of from 30:70 to 100:0.
 11. A gasoline composition as claimed in claim 1, wherein the octane booster additive is present in an amount of 0.1 to 1.0% by weight of the total weight of the gasoline composition.
 12. A method for increasing the octane number of a gasoline composition, comprising adding to the gasoline composition from 0.05 to 1% by weight of a composition comprising at least one compound according to formula I:

wherein: R₁ and R₂, independently from one another, are selected from the group consisting of linear or branched C1-C12 alkyl, C4-C12 cycloalkyl, and aryl, R₃ is H, linear or branched alkyl, cycloalkyl, or C(═O)R₄, and R₄ is linear or branched C1-C4 alkyl or C5-C6 cycloalkyl.
 13. A gasoline composition as claimed in claim 1, wherein the octane booster additive further comprises ethyl acetate.
 14. A gasoline composition as claimed in claim 1, wherein the octane booster additive further comprises esters of C1-C6 carboxylic acids and/or ketones, in a molar ratio of compound of formula I/esters of C1-C6 carboxylic acids and/or ketones of from 50:50 to 95:5.
 15. A gasoline composition as claimed in claim 1, wherein the octane booster additive is present in an amount of 0.1 to 1.0 by weight of the total weight of the gasoline composition. 